Golden perch (Macquaria ambigua) in refuge waterholes in ephemeral rivers: the effect of town proximity on biomass and size structure

Abstract

Context: Intermittent rivers make up more than 50% of the world’s rivers. Refuge waterholes in these systems are critical for survival of fish populations.Aim: This study investigated the effect that angling pressure imparts on native fish within refuge waterholes.Methods: Golden perch (Macquaria ambigua) size structure was analysed in eight refuge waterholes across three catchments of the northern Murray–Darling Basin. Waterhole characteristics were recorded, with town proximity or remoteness being adopted as a surrogate variable for angling pressure.Key results: Remoteness was found to be significantly correlated with median length, biomass, and proportion of legal-sized fish, but not with fish density. Sampling occurred after widespread connective flows, and the strength of remoteness as a predictor of median length suggests that redistribution of legal-sized golden perch on these flows was minimal. Legal-sized fish were poorly represented in the length–frequency distributions of near-town waterholes, and smaller size classes were well represented in most waterholes.Conclusion: This study suggests that populations of golden perch in refuge waterholes near towns face significant angling pressure, with impacts on size structure at a local level.Implications: These findings may have wider implications for the long-term resilience of the species.